From the site:
I've been using Scrivener for a few years now, since back when it was a Mac-only application. I was looking for an MS Word alternative because the port to Mac for MS Word was slow and lumbering. Scrivener turned out to be more than just an alternative. It's a clean, elegant platform that offers everything I need without wasting space and processor speed on anything that I don't. The application is now available for OSX, Windows, and there is even a beta for Linux users!
If you've ever heard someone disparage applications like Scrivener as "worthless bells & whistles", I'll show you some bells & whistles. These are the standard toolbars showing all of MS Word's "bells & whistles" for which you are paying not only out of your pocket, but also in drive space and processor speed:
You pay for all of that and touch next to none of it in the creation of a manuscript. I'll let you do the math.
Instead of all those "bells & whistles", you get a clean, dedicated word processor created for you, the writer, where you can manage your work in a way designed with you in mind.
Where other word processors become unwieldy and slow, trying to be jack of all trades, Scrivener is devoted to just one thing: The creation of a manuscript. You can set your workspace to your liking. Font, font size, background color, all of this can be set to what works best for you on-screen, and has no effect at all on the professional end manuscript format that Scrivener compiles for you.
If you're a planner, Scrivener will be a pleasure, allowing you to handle your novel as an outline, keeping track of chapters and scenes that can be easily moved and shifted if you find a scene needs to come earlier or later, dividing and joining with ease. If your project is research intensive, Scrivener will house almost any file type you can throw at it, keeping everything in a Research area within your project. Everything at your fingertips, all in one place. I really can't say enough about this application.
Scrivener offers a 30 day, full function trial. Not one of those beta trials where only half the features work. Plenty of time to decide if it's right for you.
P.S. Scrivener 2.7 has just been released giving full compatibility with the new features in OSX 10.11 El Capitan and also integration with the long-anticipated mobile version of Scrivener!